This invention relates to acoustic wave couplers and especially to SAW couplers in which the amount of acoustic wave power switched between waveguides is controllable.
In the field of surface acoustic waves (SAW's), the use of waveguides within which to propagate the SAW's has been found advantageous since the practice permits higher power densities and the miniaturization of signal processing devices. Inevitably, employment of waveguides leads to situations where coupling between waveguides becomes necessary.
The prior art has used passive coupling between waveguides, varying the amount of switched power by the geometry of the guides at the coupling conjunctions and by the characteristics of the guide and substrate materials. Once these are chosen, however, the amount of coupling is fixed for a particular coupler. It is obvious, of course, that it would be desirable to have available a coupler in which the amount of power switched between one guide and another could be controlled.